The present invention provides a transmission rate control method for controlling the transmission rate of uplink user data, including the step of; a radio network controller notifies to a radio base station and a mobile station an effective period of an absolute transmission rate control channel, when a call is established or when a serving cell is changed; a radio base station determines whether or not to transmit the absolute transmission rate control channel to each of mobile stations which is performing a communication with the radio base station; and each of the mobile stations determines the transmission rate of the uplink user data, based on a maximum allowable transmission rate mapped to the absolute transmission rate control channel notified by the radio base station.